1. Field of the Invention
The present invention relates to a golf club head having a rust-resistant coating for reinforcing a surface thereof. More particularly, the present invention relates to the golf club head having a rust-resistant coating layer which has a predetermined ratio of iron, cobalt and nickel, and performs a relatively high degree of the antirust ability and hardness.
2. Description of the Related Art
A conventional golf club head generally uses soft iron materials, low carbon steel or low alloy steel for example, having a relatively low degree of hardness so as to possess a greater control of striking a golf ball. The soft iron material used in the golf club head can extend a period of impacting time of the golf ball so that the golf club head is capable of controlling variations in rotations and flying directions within a certain extent while striking the golf ball. Disadvantageously, the soft iron material of the golf club head can be naturally and easily oxidized such that the material of the golf club head gathers or produces unwanted rust on its surface in normal usage of striking the golf ball.
To solve the above problem, the golf club industry made many attempts in various alloy metals in manufacturing the golf club head. Typically, a rust-resistant coating layer such as a nickel-coating or chromium-coating layer formed on a surface of the golf club head is widely used in the golf club head industry. In this way, the rust-resistant coating layer provides its antirust performance for the surface of the golf club head. For example, such a rust-resistant coating layer is disclosed in U.S. Pat. No. 5,131,986, entitled “golf club head and its manufacturing,” U.S. Pat. No. 6,617,050, entitled “low density and high ductility alloy steel for a golf club head” and U.S. Pat. No. 6,679,787, entitled “golf shaft and golf club having the same” etc.
However, the constructional property of the nickel-coating or chromium-coating layer does not appear a sufficiently fine surface which is particularly formed on a surface of the golf club head with a higher degree of roughness. This disadvantage apparently occurs in electrochemical reaction. Accordingly, rustiness still occurs on 3% of the coated surface of the golf club head in a long-term salty mist test.
Hence, there is a need for improving the rust-resistant coating layer forming on the surface the golf club head body so as to enhance the antirust ability and hardness but to maintain its mechanical strength. Therefore, the application of the rust-resistant coating layer can be widened.
The present invention intends to provide a golf club head having a rust-resistant coating layer made from a Fe—Co—Ni alloy which has a predetermined ratio of iron, cobalt and nickel. The Fe—Co—Ni alloy of the rust-resistant coating layer includes iron of 5-20 wt %, cobalt of 5-25 wt % and nickel of 60-90 wt %, possesses the performance of a nanometer-scaled material, and carries out a high degree of a combination of the antirust ability and hardness in such a way to mitigate and overcome the above problem.